This protocol hypothesizes that use of combination antiretroviral therapy will allow long-term control of viral replication with preservation of normal immune function when administered early in life to HIV-1 infected children. Specifically, this study will examine the antiretroviral activity of ZDV/3TC/NVP/NFV in vertically-infected infants and children aged >15 days to 29 days, and d4T/3TC/NVP/ NFV in vertically-infected infants and children aged >30 days. Laboratory assays will be conducted in order to assess HIV-1 and CD4/CD8 T cell kinetics, activation, and maturation. The study will also test the concept that early (< 3 months of age) use of potent, combination antiretroviral therapy will allow the long term control of viral replication with preservation of normal immune function.